JD4600 - engine just quit and won't crank over

[DanMc77]

So, yesterday I was digging a ditch with my 4600 and everything was going just great. I had been piling up muddy soil on the road from the ditch and eventually needed to get the machine to the other side of the muddy pile. So I just drove the tractor over and through the mud. The mud pile was deep enough to reach the rear axle and ooze in around some of the lower parts of the rear end. I was having to help push the machine over the mud with the backhoe. It was at this point when the engine just abruptly quit and wouldn't even crank over. When I turned the key from off to run, the familiar fuel shut off solenoid click wasn't happening. I know that this is not due to the thermister, because I have replaced the thermister with a pushbutton, and the thermister would not inhibit the engine from cranking over.

After some thought I figured that the most urgent thing was to get the machine out of the mud so it could dry out. By removing the fuel shutoff solenoid and hot-wiring the starter, I was able to get it running again and get it out and the mud hosed off. I'm not sure if the mud is a factor in this, but I figured I'd include it because at this point I don't know what's going on.

Any ideas on what interlock is in there that would even inhibit cranking the engine? Would the seat switch do this? On my tractor, there is no seat switch.

 

[Tx Jim]

Did you check for a loose wire on neutral start switch?

 

[Deleted member 216442]

So, yesterday I was digging a ditch with my 4600 and everything was going just great. I had been piling up muddy soil on the road from the ditch and eventually needed to get the machine to the other side of the muddy pile. So I just drove the tractor over and through the mud. The mud pile was deep enough to reach the rear axle and ooze in around some of the lower parts of the rear end. I was having to help push the machine over the mud with the backhoe. It was at this point when the engine just abruptly quit and wouldn't even crank over. When I turned the key from off to run, the familiar fuel shut off solenoid click wasn't happening. I know that this is not due to the thermister, because I have replaced the thermister with a pushbutton, and the thermister would not inhibit the engine from cranking over.

After some thought I figured that the most urgent thing was to get the machine out of the mud so it could dry out. By removing the fuel shutoff solenoid and hot-wiring the starter, I was able to get it running again and get it out and the mud hosed off. I'm not sure if the mud is a factor in this, but I figured I'd include it because at this point I don't know what's going on.

Any ideas on what interlock is in there that would even inhibit cranking the engine? Would the seat switch do this? On my tractor, there is no seat switch.

I have a 1070 which is the predecessor to your 4600. Mine has a seat safety switch, so if yours is built similar and you have not bypassed it you may have issues with the switch. At about 1500 hours I started having occasional engine cutout events, usually on a side hill, but got restarts. I was chasing the issue with fuel filters. Then one day it cut out and was not restarting. Filters were clean. Turned out there is a little pin which slides through a hole under the seat which is spring loaded and operates the seat safety switch. It wore a shelf into that pin which was hanging up on the edge of the hole, and that stopped the tractor like I wasn't sitting in the seat. The pin can not be seen until the seat is disassembled. Cost was a few bucks but it caused major issues. The seat safety switch will kill the engine if a pto is engaged or the tractor is in gear if you don't sit on the seat. With that worn pin the pin held the seat and my weight up like I wasn't sitting there.

 

[Egon]

After you get all the mud hosed off start checking all the safety switches and wires underneath. You'll probably find the culprit quite quickly.

 

[jthibodeau89]

Neutral safety or mid PTO switches are likely culprits. Both will inhibit cranking.

 

[DanMc77]

I was wrong in stating that there is no seat switch in my tractor. I guess I was making that conclusion because there has never been a time when it shut down because I was not in the seat. I tested the switch with a meter and it's fine.

I figured it would be easy to just go through the fuseblock and check each fuse. There's one that's labelled "Interlock" (F5) that was blown. It's a 10A fuse but I only had a 20A on hand. Dropped that in there and now it starts and runs fine. Just to be safe, I pulled the fuse and put my meter across the terminals while I started the tractor. It never measures more than .45 amps. So I'm left with the mystery: Why did that fuse blow? Obviously, there was a temporary short somewhere, but where?